Mask based toner reduction

ABSTRACT

Systems and methods for reducing toner usage. A print job is received into a print engine. The print engine comprises a processor, and the print job comprises an image. A halftone screen is applied to the pixels of continuous image data for the image. The processor produces a threshold array of pixel values based on the halftone screen. The processor generates a mask based on the halftone screen for each color plane of the image. The processor applies the mask to the threshold array, creating a modified threshold array. The modified threshold array corresponds to relatively reduced toner usage for rendering the image.

BACKGROUND

Systems and methods herein generally relate to machines having printengines such as printers and/or copier devices and, more particularly,to color management in image/text printing.

Conventional digital reprographic systems receive electronic image(s),which are passed to an image-processing unit. The image-processing unitmay be a combination of software and hardware elements that accepts theelectronic images from different sources and performs operations neededto convert the images to the format compatible with the output path ofthe digital reprographic system.

For example, a conventional image-processing unit may convert continuoustone image data into binary image data. The conventionalimage-processing unit may convert the binary image data into a reducedcoverage (economy mode or draft mode) bitmap of binary image data.Conventional digital reprographic systems convert image data into areduced coverage (economy mode or draft mode) bitmap of binary imagedata to save toner or ink usage. The economy mode may have the sameresolution as a regular print mode in a conventional digitalreprographic system, but a color table or a transfer function reducestoner or ink usage.

In general, maximizing the toner yield on an electro-photographicprinter is achieved by reducing the usage of toner in printers,especially in color printers. When printing in an economy mode, a datastream representing the image may be processed so that the printer usesless marking material (ink or toner) to print the image than it would ifthe processing was not performed. Several methods are currently in usebut there are trade-offs with respect to image quality.

The current toner savings methods can be broadly classified into thefollowing categories:

-   -   1. Reducing halftone frequency—By default, using low frequency        halftone will result in higher toner yields/cartridge or bottle.        It is easier to implement and no additional processing time is        required. It will directly lead to high toner savings at the        cost of image quality.    -   2. Adjusting tone reproduction curve (TRC)—This method is very        simple and easy to implement. The toner consumption can be        reduced with a simple adjustment to the TRC. TRC may be applied        on the halftone threshold array and the resultant threshold        array can be applied on the input image to render it. Adjusting        the TRC is very simple to implement and the processing time is        about the same as the time for applying TRC on halftone. This        TRC method will provide high toner saving with a trade-off on        quality.    -   3. Using neighborhood processing—In this method, a rendered        image (halftoned plane) is used to decide which pixel needs to        be turned on/off. This method will provide moderate toner saver        with acceptable image quality; however, it is more complex to        implement. This method requires additional processing time for a        transfer function that determines which pixels are needed to be        marked on paper (e.g., removing center pixel from a 3×3 array).    -   4. Optimizing print engine and IOT components for better toner        yields.

All of the above mentioned methods have significant impact on the imagequality. Some of these methods achieve savings by trading the quality ofoutput. In one of the methods (Controlling Colors by TRC) the colors maybe washed away, other methods create artifacts in the image; and somemethods are suitable only for Black and White.

Additionally, for color printers, each color toner is used at adifferent rate. Generally, when a printer is low on one toner, theprinter device warns the user to replace that particular toner. When thetoner level reaches a critical point, the user is unable to print anydocument until the empty toner is replaced.

SUMMARY

In one aspect of a method disclosed herein, the halftone frequency isselected based on the capability of engine such that any banding or anyother kinds of artifacts are minimized to the extent possible. Thehalftone frequency is carefully selected for all color planes such thatany moiré is avoided. With the selected frequency for each plane, athreshold array is generated and applied to the input plane to produce ahalftoned/rendered image.

According to a method herein, a print job is received into a printengine. The print engine comprises a processor, and the print jobcomprises an image. A threshold array of pixel values is produced by theprocessor for each color plane of the image based on a halftone screen.The halftone screen includes separate halftone frequencies and differentthreshold values for each color plane of the image. The halftonefrequencies and the threshold values are established during calibrationof the print engine. A mask is generated for each the color plane of theimage based on the halftone screen. Generating the mask comprisesgrouping the pixel values for the threshold array into a selected numberof clusters, arranging the clusters into a cluster array using one pixelvalue from each cluster, and identifying pixel values to remove from thethreshold array based on the location of the pixel value in the clusterarray. The mask is controlled to avoid removing two consecutive pixelsfrom the image based on the threshold array. The processor applies themask to the threshold array, creating a modified threshold array. Themodified threshold array corresponds to relatively reduced toner usagefor rendering the image.

According to another method herein, digitized pixels for an imagecomprising color planes of different colors are received. The digitizedpixels comprise continuous image data. A halftone screen is applied tothe pixels of the continuous image data. The halftone screen includesseparate halftone frequencies and different threshold values for eachcolor plane of the image. The halftone frequencies and the thresholdvalues are set during calibration of the print engine. The halftonefrequencies are based on reducing banding and image artifacts in arendered image. A threshold array of pixel values is produced byapplying the halftone screen. A mask is generated based on the halftonescreen for each of the color planes of the image. The mask is generatedby grouping the pixel values from the threshold array into a selectednumber of clusters, arranging the clusters into a cluster array usingone pixel value from each cluster, and identifying pixel values toremove from the threshold array based on location of the pixel value inthe cluster array. The mask is controlled to avoid removing twoconsecutive pixels from the image based on the threshold array. Thethreshold array of pixel values is translated to an image file. The maskis applied to the image file, removing selected pixels from the renderedimage, based on the mask.

According to a multifunction device, a control system comprises aprocessor. The processor comprises a digital image processor. A userinterface is connected to the control system. An image output device isconnected to the processor. The user interface provides user selectionof a level of toner savings for the image output device. The processorreceives digitized pixels for an image comprising color planes ofdifferent colors. The digitized pixels comprise continuous image data.The digital image processor applies a halftone screen to the digitizedpixels of the continuous image data. The halftone screen includesseparate halftone frequencies and different threshold values for eachcolor plane of the image. The halftone frequencies and the thresholdvalues are set during calibration of a print engine associated with theimage output device. The halftone frequencies are based on reducingbanding and image artifacts in a rendered image according to the imageoutput device. The digital image processor produces a threshold array ofpixel values using the halftone screen. The processor generates a maskbased on the halftone screen for each of the color planes of the image.The mask is generated by grouping the pixel values from the thresholdarray into a selected number of clusters, arranging the clusters into acluster array using one pixel value from each cluster, and identifyingpixel values to remove from the threshold array based on the location ofthe pixel value in the cluster array. The mask is controlled to avoidremoving two consecutive pixels from the image based on the thresholdarray. The processor translates the threshold array of pixel values toan image file. The processor applies the mask to the image file,removing selected pixels from the rendered image. The processor sendsthe image file to the image output device.

According to a method herein, digitized pixels for an image comprisingcolor planes of different colors are received into a print engine. Theprint engine comprises a processor. The digitized pixels comprisecontinuous image data. A halftone screen is applied to the pixels ofcontinuous image data. The halftone screen includes separate halftonefrequencies and different threshold values for each color plane of theimage. The halftone frequencies and the threshold values are set duringcalibration of the print engine. A threshold array of pixel values isproduced based on the halftone screen. A mask is generated based on thehalftone screen for each of the color planes of the image. Thegenerating of the mask comprises: grouping the pixel values for thethreshold array into a selected number of clusters, arranging theclusters into a cluster array using one pixel value from each cluster,and identifying pixel values to remove from the threshold array based onthe location of the pixel value in the cluster array. The mask iscontrolled to avoid removing two consecutive pixels from the image basedon the threshold array. The mask is applied to the threshold array,creating a modified threshold array. The modified threshold arraycorresponds to relatively reduced toner usage for rendering the image.

According to a non-transitory computer readable storage medium herein,the non-transitory computer readable storage medium stores instructionsexecutable by a computerized device to perform a method. According tothe method, digitized pixels for an image comprising color planes ofdifferent colors are received. The digitized pixels comprise continuousimage data. A halftone screen is applied to the pixels of the continuousimage data. The halftone screen has a frequency based on reducingbanding and image artifacts in a rendered image. A threshold array ofpixel values is produced using the halftone screen. A mask is generatedbased on the halftone screen for each of the color planes of the image.The threshold array of pixel values is translated to an image file. Themask is applied to the image file, removing selected pixels from therendered image.

These and other features are described in, or are apparent from, thefollowing detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Various examples of the systems and methods are described in detailbelow, with reference to the attached drawing figures, which are notnecessarily drawn to scale and in which:

FIG. 1 is a side-view schematic diagram of a multi-function deviceaccording to systems and methods herein;

FIG. 2 is a flow diagram illustrating a broad overview of a processaccording to systems and methods herein;

FIGS. 3A and 3B are a flow diagram illustrating systems and methodsherein;

FIG. 4 is a flow diagram illustrating a method according to systems andmethods herein;

FIG. 5 is a flow diagram illustrating a method according to systems andmethods herein;

FIG. 6 is a flow diagram illustrating additional method steps accordingto systems and methods herein;

FIG. 7 is a flow diagram illustrating methods herein;

FIG. 8 is a flow diagram illustrating methods herein; and

FIG. 9 is a schematic diagram illustrating systems and methods herein.

DETAILED DESCRIPTION

The disclosure will now be described by reference to a multi-functiondevice that includes a print engine having a digital image processor.While the disclosure will be described hereinafter in connection withspecific systems and methods thereof, it will be understood thatlimiting the disclosure to such specific systems and methods is notintended. On the contrary, it is intended to cover all alternatives,modifications, and equivalents as may be included within the spirit andscope of the disclosure as defined by the appended claims.

For a general understanding of the features of the disclosure, referenceis made to the drawings. In the drawings, like reference numerals havebeen used throughout to identify identical elements.

FIG. 1 illustrates a multi-function device 101 that can be used withsystems and methods herein and can comprise, for example, a printer,copier, fax machine, etc. The multi-function device 101 includes acontroller/processor 104 and an input/output device 110 operativelyconnected to the controller/processor 104. As described above, thecontroller/processor 104 may be connected and to a computerized network902 external to the multi-function device 101 through a communicationsport of the input/output device 110, such as shown in FIG. 9, describedbelow. In addition, the multi-function device 101 can include at leastone accessory functional component, such as a graphic user interfaceassembly (GUI) 113. The GUI 113 operates on power supplied from anexternal power source 122. The external power source 122 may provideelectrical power through the power supply 125.

The input/output device 110 is used for communications to and from themulti-function device 101. The controller/processor 104 controls thevarious actions of the multi-function device 101. A non-transitorycomputer storage medium 128 (which can be optical, magnetic, capacitorbased, etc.) is readable by the controller/processor 104 and storesinstructions that the controller/processor 104 executes to allow themulti-function device 101 to perform its various functions, such asthose described herein.

According to systems and methods herein, the controller/processor 104may comprise a special purpose processor that is specialized forprocessing image data and includes a dedicated processor that would notoperate like a general purpose processor because the dedicated processorhas application specific integrated circuits (ASICs) that arespecialized for the handling of image processing operations, processingimage data, calculating pixel values, etc. In one example, themulti-function device 101 is special purpose machine that includes aspecialized image processing card having unique ASICs for providingimage processing instructions, includes specialized boards having uniqueASICs for input and output devices to speed network communicationsprocessing, a specialized ASIC processor that performs the logic of themethods described herein using dedicated unique hardware logic circuits,etc. It is contemplated that the controller/processor 104 may comprise araster image processor (RIP). A raster image processor uses the originalimage description to RIP the print job. Accordingly, the printinstruction data is converted to a printer-readable language. The printjob description is generally used to generate a ready-to-print file. Theready-to-print file may be a compressed file that can be repeatedlyaccessed for multiple (and subsequent) passes.

Thus, as shown in FIG. 1, a device housing 131 has one or morefunctional components that operate on power supplied from the externalpower source 122, which may comprise an alternating current (AC) powersource, through the power supply 125. The power supply 125 can comprisea power storage element (e.g., a battery) and connects to the externalpower source 122. The power supply 125 converts the external power intothe type of power needed by the various components of the multi-functiondevice 101.

The multi-function device 101 may include at least one marking device134 (sometimes referred to as printing engines) operatively connected tothe controller/processor 104, a media path 137 positioned to supplysheets of media from a media supply 140 to the marking device(s) 134,etc., along the media path 137. After receiving various markings fromthe printing engine(s), the sheets of media can optionally pass to afinisher 143 which can fold, staple, sort, etc., the various printedsheets. In addition, the multi-function device 101 can include at leastone accessory functional component (such as a scanner/document handler146, fax module 149, etc.) that also operates on the power supplied fromthe external power source 122 (through the power supply 125). The faxmodule 149 may operate in conjunction with the scanner/document handler146.

The scanner/document handler 146 may be any image input device capableof obtaining information from an image. The set of image input devicesis intended to encompass a wide variety of devices such as, for example,digital document devices, computer systems, memory and storage devices,networked platforms such as servers and client devices which can obtainpixel values from a source device, and image capture devices. The set ofimage capture devices includes scanners, cameras, photography equipment,facsimile machines, photo reproduction equipment, digital printingpresses, xerographic devices, and the like. A scanner is one imagecapture device that optically scans images, print media, and the like,and converts the scanned image into a digitized format. Common scanningdevices include variations of the flatbed scanner, generally known inthe art, wherein specialized image receptors move beneath a platen andscan the media placed on the platen. Modern digital scanners typicallyincorporate a charge-coupled device (CCD) or a contact image sensor(CIS) as the image sensing receptor(s). The scanning device produces asignal of the scanned image data. Such a digital signal containsinformation about pixels such as color value, intensity, and theirlocation within the scanned image.

Further, an image output device is any device capable of rendering theimage. The set of image output devices includes digital documentreproduction equipment and other copier systems as are widely known incommerce, photographic production and reproduction equipment, monitorsand other displays, computer workstations and servers, including a widevariety of color marking devices, and the like.

To render an image is to reduce the image data (or a signal thereof) toviewable form; store the image data to memory or a storage device forsubsequent retrieval; or communicate the image data to another device.Such communication may take the form of transmitting a digital signal ofthe image data over a network.

As would be understood by those ordinarily skilled in the art, themulti-function device 101 shown in FIG. 1 is only one example and thesystems and methods herein are equally applicable to other types ofprinting devices that may include fewer components or more components.For example, while a limited number of printing engines and paper pathsare illustrated in FIG. 1, those ordinarily skilled in the art wouldunderstand that many more paper paths and additional printing enginescould be included within any printing device used with systems andmethods herein.

As shown FIG. 2, an incoming job may include a PDL file 205 thatdescribes the appearance of a printed page according to the job. Theinput may be a page description using a page description language (PDL).A page description language (PDL) is a computer language that describesfor the print engine the appearance of a printed page in a higher levelthan an actual output bitmap. The PDL file 205 specifies the arrangementof the printed page through commands for the print engine. Aninterpreter 208 may be used in a preprocessing step to interpret aspecified number of job pages.

An exemplary processing system may include an interpreter 208 and animager 211, as shown in FIG. 2. The interpreter 208 and imager 211 areclassic components of a two-part raster image processor (RIP), such asmay be used to prepare the job for printing. As would be known by oneskilled in the art, a raster image processor is a component used in aprinting system that produces a raster image, also known as a bitmap.The bitmap is then sent to a printing device for output. Raster imageprocessing is the process that turns the job input information into ahigh-resolution raster image. The input may be a page description usinga page description language (PDL) of higher or lower resolution than theoutput device. In the latter case, the RIP applies either smoothing orinterpolation to the input bitmap to generate the output bitmap.

According to systems and methods herein, the interpreter 208 parses thePDL file 205 according to PDL-specific language constructs, and changesthese into pdl-language neutral “objects” that are presented to theimager 211 for collection. In this way, various language-specificinterpreters can be mated with a single imager implementation.

To print an image, a print engine processor, sometimes referred toherein as an image processor, converts the image in a page descriptionlanguage or vector graphics format to a bit mapped image indicating avalue to print at each pixel of the image. Each pixel may represent adot, also called a picture element. The sequence of dots forming acharacter is called a raster pattern. The number of dots per inch that aprinter generates is called the print resolution, or density. Aresolution of 240 pixels means that a printer prints 240 pixels per inchboth vertically and horizontally, or 57,600 pixels per square inch(240×240).

Each bit representing a pixel that is “on” is converted to an electronicpulse. The electronic pulses generated from the raster pixel data atwhich to deposit toner turns the laser beam on to positively charge thesurface of a rotating drum, which is an organic photo-conductingcartridge (OPC), that has a coating capable of holding an electrostaticcharge. The laser beam turns on and off to beam charges at pixel areason a scan line across the drum that will ultimately represent the outputimage. After the laser beam charges all pixels on the scan lineindicated in the raster data, the drum rotates so the laser beam canplace charges on the next scan line. The drum with the electrostaticpositive charges then passes over negatively charged toner. Thenegatively charged toner is then attracted to the positive charged areasof the drum that form the image. The paper, which is negatively charged,passes over the roller drum and attracts the toner as the areas of theroller drum with the toner are positively charged to transfer the tonerforming the image from the roller drum to the paper.

Many laser printers may filter the bit map images using a look-up tableto alter the pulses generated for each pixel to accomplish a certainfiltering result. For instance, filters can be used to provide aneconomy mode where toner is reduced, to remove jagged edges, improveprint quality enhancement, or to reduce the density of images.Typically, the laser printer will gather an area of data and replaceeither one or all the pulse values for the pixels based on the gatheredarea of pixel data matching a value in the look-up table. Such look-uptables modify the pixel output by altering the pulse normally used foran “on” pixel value with a pulse width modulator to shorten the pulsewidth to reduce the electric charge the laser beam places on the roller.Reducing the pulse width reduces the charged area for the pixel on theroller and, hence, reduces the amount of toner attracted to the rollerfor that pixel, thus reducing the amount of toner used to represent thepixel.

One technique to reduce toner usage is referred to as sub-pulse widthmodulation. In this method, the laser current applied to each pixel areaon the roller is reduced in order to reduce the area of the electricalcharge applied to the pixel position on the roller, thereby attractingless toner. This technique requires that the laser be continuouslyswitched on and off within each pixel to place a sub-pixel charge in aportion of the pixel on the roller.

Another technique to reduce toner usage is to apply a single symmetricalscreen pattern, e.g., a checkerboard, over the total image in order tosubtract pixels from the image. Thus, the entire black area of an imageis replaced with a checkerboard pattern to reduce in half the number ofpixels to which toner is attracted. The problem with this approach isthat, because data is removed without any consideration to the imagestructure, it is possible that the screen pattern would deletesignificant portions of the image, such as edge pixels that form theoutline of the image. This reduces the edge resolution and quality ofthe image resulting in a “washed-out” appearance.

It is contemplated that the systems and methods described herein areapplicable to color marking material as well as simple black markingmaterial. A contone is a characteristic of a color image such that theimage has all the values (0 to 100%) of gray (black/white) or color init. A contone can be approximated by millions of gradations ofblack/white or color values. The granularity of computer screens (i.e.,pixel size), however, can limit the ability to display absolutecontones. The term halftoning refers to a process of representing acontone image by a bi-level image such that, when viewed from a suitabledistance, the bi-level image gives the same impression as the contoneimage. For example, in printing, a contone image, such as a photograph,may be converted into a black-and-white image. Halftones of black andwhite shades are created through a process called dithering, in whichthe density and pattern of black and white pixels are varied to simulatedifferent shades of gray. Halftoning reduces the number of quantizationlevels per pixel in a digital image. Over the long history ofhalftoning, a number of halftoning techniques have been developed whichare adapted for different applications.

In conventional printing, halftones are created by processing the imagethrough a sort of ‘screen’. The frequency, measured in lines per inch,determines how many pixels are used to make each spot of gray. That is,the halftone-screen frequency determines the number of dots used tocreate the image. In theory, the higher the screen frequency (the morelines per inch), the more accurate the halftone will be. However, actualscreen frequencies are limited by the technology because higher screenfrequencies create smaller, more tightly packed dots. Traditionally,clustered dot halftones were restricted to a single frequency becausethey were generated using periodic gratings that could not be readilyvaried spatially. Halftoning techniques are widely employed in theprinting and display of digital images and are used because the physicalprocesses involved are binary in nature or because the processes beingused have been restricted to binary operation for reasons of cost,speed, memory, or stability in the presence of process fluctuations.Classical halftone screening applies a mask of threshold values to eachcolor of the multi-bit image. Thresholds are stored as a matrix in arepetitive pattern. Each tile of the repetitive pattern of the matrix isa halftone cell. Digital halftones generated using threshold arrays thattile the image plane were originally designed to be periodic forsimplicity and to minimize memory requirements. With the increase incomputational power and memory, these constraints become less stringent.Digital halftoning uses a raster image or bitmap within which eachmonochrome picture element or pixel may be ON or OFF (ink or no ink).Consequently, to emulate the photographic halftone cell, the digitalhalftone cell must contain groups of monochrome pixels within thesame-sized cell area.

As mentioned above, toner yield can be extended by reducing the halftonefrequency. In addition, the methods described herein provide furthertoner saving while maintaining acceptable image quality for either coloror mono products/printers. According to systems and methods herein, thehalftone frequency is selected based on the capability of the printengine such that any banding or other kinds of artifacts are minimized.The halftone frequency is carefully selected for each of the colorplanes (cyan, magenta, yellow, and black (CMYK)) such that any moiré isavoided. With the selected frequency for each color plane, a halftonethreshold array is generated and set at calibration of the image outputdevice. The halftone threshold array may include different thresholdvalues for each color as part of the calibration of the printer. Thehalftoning process applies the calibrated threshold array to ahigher-bit (contone) input image to produce a lower-bit,halftone/rendered image.

Referring to FIGS. 3A and 3B, a mask is generated based on the halftonescreen for each color plane of the image in order to reduce the tonerusage further, following the halftone step. That is, as shown in FIG.3A, the first step, indicated at 303, is to initialize the mask. Theinitial halftone threshold array 306 includes threshold values between 0and 255. A matrix is created from the initial halftone threshold array306 in which the row values correspond to the height of the thresholdarray and the column values correspond to the width of the thresholdarray.

According to systems and methods herein, the halftone threshold arrayfrom the halftone screen is modified based on the mask for eachindividual color plane that was used to produce the lower-bithalftone/rendered image. The mask can be applied in two ways: first, themask may be applied directly on the halftone threshold array, asdescribed below with reference to FIG. 4; second, the mask may beapplied on the rendered image, as described below with reference to FIG.5. Note: applying the mask directly on the halftone threshold arrayrequires no additional processing time; applying the mask on therendered image requires little additional processing time, since it is asimple multiplication operation.

At 309, the next step in creating the mask is to create clusters fromthe pixel values in the halftone threshold array 306. That is, thethreshold values (e.g., 0-255 for an 8-bit array) are grouped into ‘N’number of clusters 312. It is not necessary to have an equal number ofvalues in each cluster. For example, the threshold values may be groupedinto four clusters, such as: Cluster-A (0-64), Cluster-B (65-128),Cluster-C (129-192), and Cluster-D (193-255). Other numbers of clustersand pixel threshold values may be used.

The next step, as shown at 315, is to arrange the clusters to form theCluster_Array 318. For example, to arrange one pixel from each cluster,an arrangement might look like something like D-C-B-A:

[Cluster-D (1) Cluster-C (1) Cluster-B (1) Cluster-A (1)

Cluster-D (2) Cluster-C (2) Cluster-B (2) Cluster-A (2) . . . ]

Temp=[193 129 65 0 194 130 66 1 195 131 67 2 . . . ]

According to systems and methods herein, the Cluster_Array 318 may bearranged by picking one value from each group/cluster. Selection of thenumber of clusters and arrangement of the clusters depends on thecapability of the print engine 134 and the halftone screen of the device101. For example, a different resolution printer may arrange clusters asC-A-D-B.

Referring now to FIG. 3B, the mask creation 321 is illustrated as aniterative process. If processing is performed sequentially from zero,more threshold values may be removed in lower tone level; therefore,there may not be sufficient saving in mid and high tone levels. Pixelvalues to remove from the threshold array 306 are identified based onthe location of the pixel value in the Cluster_Array 318. Accordingly,in order to achieve adequate toner savings in all levels, pixel valuesare removed from different tone levels (i.e., clusters). This isachieved by cluster formation and cluster arrangement, as describedherein. As mentioned above, selection of the number of clusters andarrangement of the cluster depends on the capability of the print engine134 and the halftone screen of the device 101. For example, a printengine with higher halftone frequency capability may be able to use moreclusters.

As shown in FIG. 3B, the first step is to initialize the loop function324. At 327, the Cluster_Array 318 starts from the halftone thresholdarray 306. Next, at 330, mask creation is performed for each pixel alongthe length of the array. The Resultant_mask is created based on thepixel levels, at 333. Note: when an active pixel is placed in the maskit should not have any neighborhood pixels in the mask; otherwise, itmay lead to artifacts in the printed image. If, at 336, an active pixelis found in a 3×3 portion of the array, the process reverts to the nextpixel in the row. That is, an active pixel in the mask indicates thelocation to remove the pixel value from the halftone threshold array 306or the rendered image. Once each pixel is evaluated according to themask, the Resultant_mask is made active at 339.

A sample pseudo-code for mask creation 321 is shown below:

[r_idx c_idx]= Threshold_Array==Temp(1) Mask[r_idx][c_idx]=1; % settingmask active. for i=2 to length of Temp   [r_idx c_idx]= Threshold_Array==Temp(1)   If eight neighborhood pixels around Mask[r_idx][c_idx]   isnot active     Mask[r_idx][c_idx]=1; % setting mask active   end endNote: the last step of the pseudo-code is used to ensure that the maskdoes not remove two consecutive pixels. Removing any two or moreconsecutive pixels in any direction will lead to unnecessary artifactsand is not desired.

Referring now to FIG. 4, the mask can be applied on the halftonethreshold array. The resultant array can be used as a modified halftonethreshold array, which may be sent to a marking device. In particular,as would be known to one of ordinary skill in the art, the halftoningprocess applies the calibrated halftone threshold array to thehigher-bit (contone) input image to produce a lower-bit, halftone image,as shown at 413. As described above, the halftone frequency is selectedfor all color planes, based on the capability of the print engine. Thisis a one-time process, based on the particular machine in which thehalftone threshold array is created from the different halftonefrequencies for each color plane during calibration. The mask isgenerated, as indicated at 416. Again, as the mask generation 416 isbased on the threshold array, this is a one-time process. Then, at 419,the mask is applied to the threshold array 413, which produces amodified threshold array 422. The modified threshold array 422 is usedto render an image from the input contone image, as indicated at 425.The rendered image may then be sent for marking by the marking device,as shown at 428. In other words, with the selected frequency for eachcolor plane, a modified threshold array 422 is generated and applied tothe input plane to produce a halftone/rendered image with a maskapplied.

Below are tables showing pixel counts for testing results on severalsample pages with approximately low area coverage (20%) and high areacoverage. In order to determine the savings in toner, the starting pixelcount values were determined from a rendered image (bitmap) using aninitial halftoning process, as is known in the art. Table 1 shows thestarting pixel counts for five different test pages using a printerwithout using the toner savings described herein.

TABLE 1 Pixel counts from a sample printer with no toner savingsOriginal Cyan Magenta Yellow Black Testpage 1 0 23230 20509 1321168Testpage 2 1775736 1261527 1316406 1026629 Testpage 3 761674 9934461357979 2505746 Testpage 4 1712931 2192970 2373544 357360 Testpage 52556048 2185226 2580895 1174241

Table 2 shows the pixel counts from the same printer after a mask isapplied, i.e., this is the result from the modified threshold array.

TABLE 2 Pixel counts from modified threshold array Saving Method CyanMagenta Yellow Black Testpage 1 0 19066 16306 1056962 Testpage 2 12342151033695 1077786 821668 Testpage 3 565452 839579 992400 2003131 Testpage4 1234791 1768796 1853621 286029 Testpage 5 1860329 1758736 1910175936063

Table 3 shows the percentage reduction between the test page with notoner savings (Table 1) and application of the modified threshold array(Table 2). As shown in Table 3, this method averages approximately 20%reduction in toner consumption.

TABLE 3 Percentage reduction in pixel counts Pixel Reduction in % Cyan %Magenta % Yellow % Black % Testpage 1 0 17.93 20.49 20.00 Testpage 230.50 18.06 18.13 19.96 Testpage 3 25.76 15.49 26.92 20.06 Testpage 427.91 19.34 21.90 19.96 Testpage 5 27.22 19.52 25.99 20.28

As illustrated above, the method optimizes toner usage while maintainingimage quality. That is, visually the method does not exhibit anysignificant loss in image quality while still maintaining the overalldynamic color range.

Referring now to FIG. 5, the mask can be used to remove pixels from arendered image. In this case, the mask can be applied in postprocessing, if applicable. In particular, as would be known to one ofordinary skill in the art, the halftoning process applies the calibratedhalftone threshold array to the higher-bit (contone) input image toproduce a lower-bit, halftone image, as shown at 524. As describedabove, halftone frequencies are selected for all color planes, based onthe capability of the print engine. This is a one-time process, based onthe particular machine in which the halftone threshold array is createdfrom the different halftone frequencies for each color plane duringcalibration. The threshold array 524 is applied to the input contoneimage, as indicated at 527. Such a process produces a rendered image, asindicated at 530. Meanwhile, the mask is generated, as indicated at 533.Again, as the mask generation 533 is based on the threshold array, thisis a one-time process. The mask generation 533 can be scaled so that theimage output device can provide the option of choosing the relativelevel of toner saving (e.g., low, medium, or high toner savings). Asshown at 536, a user can select the relative level of toner saving.Then, at 539, the appropriate mask is selected and applied to therendered image 530. The rendered image 530 may then be sent for markingby the marking device, as shown at 542. In other words, with theselected frequency for each plane, a threshold array 524 is generatedand applied to the input plane to produce a halftone/rendered image 530.The mask is then applied to remove pixels from the rendered image. Asdescribed above, during formation of the mask, the clustering iscontrolled to avoid removing two consecutive pixels from the array (toallow virtually unnoticeable toner reduction).

Note: in the methods described herein, the mask is derived from thehalftone threshold array, which provides more control on the tonersavings as well as quality of the image. According to systems andmethods herein, toner usage is optimized while maintaining imagequality. Such control is not possible to this extent in other methods.As described above, the level of toner savings can be controlled bymodifying the number of clusters and in the arrangement of the array.This enables the option to provide for the user to select the level oftoner savings (e.g., low toner saving, medium toner saving, and hightoner saving).

After a given page in the job has been processed as described above,each subsequent page of the job to be processed is treated in the sameway. Note that it is not necessary for the “imager” used in theprocessor to actually produce an image. Print-ready images may becreated later when the job is processed for printing.

Additionally, as noted above, for color printers, each color toner maybe used at a different rate. It is contemplated that most printing isperformed with specific colors repeatedly. Accordingly, one or more ofthe colors (Cyan/Magenta/Yellow/Black) may be over utilized such thatthe toner cartridge for the printer may run out of toner for thoseparticular color(s). When the toner level reaches a critical point, theuser is unable to print any document until the empty toner is replaced.In order to afford the user time to place a purchase order for tonerbetween the low-level warning and the error message that may stop theprinter, the life of the toner cartridge may be extended for a shortperiod between those times by applying the mask to only specific colorplanes in the threshold array having the low toner condition. Forexample, according to devices and methods herein, a switch may beprovided on the printer in order to switch between ‘high-quality’ and‘high-throughput’ printing modes based on the toner level. Alternativelyor in addition, the print quality mode for the image output device maybe automatically set to an economical ‘toner saver’ mode as a default. Aswitch may be enabled on the printer on a color-by-color basis so thatthe toner saver is applied only to the color having a low level oftoner.

To utilize the toner cartridges in an effective manner, the system mayautomatically detect toner cartridge level when it falls below aspecific threshold level (for example: Cyan toner cartridge level dropsbelow 25%). Then the printer will swap the default halftone of thatparticular color with a respective modified halftone threshold based onthe appropriate mask applied to the halftone threshold array.Alternatively, the printer can activate the toner saver process in postprocessing in which the mask is applied to remove only the particularcolor pixels from the rendered image. Succeeding prints, after thewarning, will use less toner for the specific color or colors havingtoner level below the selected threshold. This provides the user withextra time to replace the low toner cartridge while still continuing toprovide print capability.

Referring to FIG. 6, the toner level is determined for each of thecolors for the machine, at 615. A sensor or other known device may beused to determine the amount of toner for each color available forprinting and provide an indication of toner level. Typically, the colorsare cyan, magenta, yellow, and black (CMYK). A separate sensor can beused for each color. At 618, a processor in the printing devicedetermines if the toner level for any color is below a predeterminedthreshold. If, at 618, none of the toner cartridges is below thepredetermined threshold, the process continues with ‘high-quality’halftone processing 621. The ‘high-quality’ halftone processing 621 mayinclude applying the calibrated halftone threshold array to the inputbitmap 624, as indicated at 627. This produces a halftoned image 630,which may then be sent for marking by the marking device, as shown at633. If, at 618, any one of the toner cartridges is below thepredetermined threshold level, the process continues with‘high-throughput’halftone processing 636. The ‘high-throughput’ halftoneprocessing 636 may include applying a mask to the calibrated halftonethreshold array for only the toner color having low level cartridge inorder to produce a modified threshold array for the selected color, asdescribed above with reference to FIG. 4. The modified threshold arrayis then applied to the input bitmap 624, as indicated at 627. Thisproduces a halftoned image 630, which may then be sent for marking bythe marking device, as shown at 633.

One of the unique aspects of this solution is that, in the‘high-throughput’ halftone processing, toner saving is used only onthose colors that are under the threshold established on the printer.This process may be selectively applied so that it will not affect theother colors that do not have a low toner warning. Therefore, when aprint job does not have any pixels being requested with the low tonercolor, there will be no difference in the output. Additionally, thethreshold level may be established on the printer such that a user willnot be able to change this threshold level. However, it is contemplatedthat this method can be scaled up or down so that the printer canprovide the option of selecting the relative level of toner saving.

Furthermore, since the switch from the default print quality mode to the‘toner saver’ print quality mode is done at the processing level and notas a job level setting, it is expected that there will be no performancedegradation. Upon replacing the toner, the ‘high-throughput’ (TonerSaver) halftones are replaced with the default halftones on allsubsequent jobs.

FIG. 7 is a flow diagram illustrating the processing flow of anexemplary method according to systems and methods herein. At 712, aprint job is received into a print engine. As indicated at 724, theprint engine includes a processor, and the print job includes an image.At 736, a threshold array of pixel values is produced by the processorfor each color plane of the image based on a halftone screen. Asindicated at 748, the halftone screen includes separate halftonefrequencies and different threshold values for each color plane of theimage. The halftone frequencies and the threshold values are set duringcalibration of the print engine. At 760, the processor generates a maskbased on the halftone screen for each color plane of the image. The maskis generated by grouping the pixel values from the threshold array intoa selected number of clusters, arranging the clusters into a clusterarray using one pixel value from each cluster, and identifying pixelvalues to remove from the threshold array based on the location of thepixel value in the cluster array. The mask is controlled to avoidremoving two consecutive pixels from the image based on the thresholdarray. At 772, the processor applies the mask to the threshold array,creating a modified threshold array. The modified threshold arraycorresponds to relatively reduced toner usage for rendering the image.

FIG. 8 is a flow diagram illustrating the processing flow of anexemplary method according to systems and methods herein. At 811,digitized pixels for an image comprising color planes of differentcolors are received into a print engine. As indicated at 822, the printengine includes a processor. At 833, a halftone screen is applied, bythe processor, to the pixels of continuous image data. As indicated at844, the halftone screen includes separate halftone frequencies anddifferent threshold values for each color plane of the image. Thehalftone frequencies and threshold values are set during calibration ofthe print engine. The halftone frequencies are based on reducing bandingand image artifacts in a rendered image. As indicated at 855, athreshold array of pixel values is produced by applying the halftonescreen. At 866, the processor generates masks based on the halftonescreen for each color plane of the image, at 877. The masks aregenerated by grouping the pixel values from the threshold array into aselected number of clusters, arranging the clusters into a cluster arrayusing one pixel value from each cluster, and identifying pixel values toremove from the threshold array based on location of the pixel value inthe cluster array. Multiple masks can be created for selected levels oftoner savings (e.g., low toner saving, medium toner saving, and hightoner saving), as indicated at 877. The mask is controlled to avoidremoving two consecutive pixels from the image based on the thresholdarray. At 888, the threshold array of pixel values is translated to animage file. At 899, the processor applies the mask to the image file toremove pixels from the rendered image.

As used herein, a “pixel” refers to the smallest segment into which animage can be divided. Received pixels of an input image are associatedwith a color value defined in terms of a color space, such as color,intensity, lightness, brightness, or some mathematical transformationthereof. Pixel color values may be converted to a chrominance-luminancespace using, for instance, an RGB-to-YCbCr converter to obtain luminance(Y) and chrominance (Cb,Cr) values. It should be appreciated that pixelsmay be represented by values other than RGB or YCbCr.

As shown in FIG. 9, exemplary printers, copiers, multi-functionmachines, and multi-function devices (MFD) 101 may be located at variousdifferent physical locations 906. Other devices according to systems andmethods herein may include various computerized devices 908. Thecomputerized devices 908 can include print servers, printing devices,personal computers, etc., and are in communication (operativelyconnected to one another) by way of a network 902. The network 902 maybe any type of network, including a local area network (LAN), a widearea network (WAN), or a global computer network, such as the Internet.

The hardware described herein plays a significant part in permitting theforegoing method to be performed, rather than function solely as amechanism for permitting a solution to be achieved more quickly, (i.e.,through the utilization of a computer for performing calculations). Forexample, these methods reduce the usage of toner when customers arewilling to trade slight quality deprecation for cost efficiency.Therefore, such processes as creating a mask and applying the mask to animage require the use of a computerized image processor to both accessthe image and to process the image.

As would be understood by one ordinarily skilled in the art, theprocesses described herein cannot be performed by human alone (or oneoperating with a pen and a pad of paper) and instead, such processes canonly be performed by a machine. Specifically, processes such asprinting, scanning, electronically altering images using an imageprocessor etc., require the utilization of different specializedmachines. Therefore, for example, the production of a threshold array ofpixel values based on a halftone screen, creation of a mask based on thehalftone screen for each color plane of an image, and printing/scanning,which are performed by the devices herein, cannot be performed manually(because machines are required to perform digital image processing andprinting) and such devices are integral with the processes performed bymethods herein. Further, such machine-only processes are not mere“post-solution activity” because the automated analysis of each imagecolor plane by an image processor is integral with the steps of theprocesses described herein. Similarly, the receipt of a print job andconversion of data utilize special purpose equipment (telecommunicationsequipment, routers, switches, etc.) that is distinct from ageneral-purpose processor. In other words, these various machines areintegral with the methods herein because the methods cannot be performedwithout the machines (and cannot be performed by humans alone).

Additionally, the methods herein solve many highly complex technologicalproblems. For example, the toner yield on an electro-photographicprinter can be maximized by reducing the usage of toner withoutincreasing processing time. Methods herein solve this technologicalproblem by combining halftone reduction with a mask applied to thehalftone threshold array. This is especially useful in solving thistechnological problem because it provides reduced toner usage withdramatically reduced quality degradation as compared to othertoner-reduction techniques. By providing such benefits, the methodsherein reduce the amount and complexity of hardware and software neededto be purchased, installed, and maintained by those attempting to reducethe usage of toner with only slight quality deprecation for costefficiency, thereby solving a substantial technological problem that isexperienced today.

Aspects of the present disclosure are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to various systemsand methods. It will be understood that each block of the flowchartillustrations and/or two-dimensional block diagrams, and combinations ofblocks in the flowchart illustrations and/or block diagrams, can beimplemented by computer program instructions. The computer programinstructions may be provided to a processor of a general purposecomputer, special purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor of the computer or other programmabledata processing apparatus, create means for implementing thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

According to a further device and method herein, an article ofmanufacture is provided that includes a tangible computer readablemedium having computer readable instructions embodied therein forperforming the steps of the computer implemented methods, including, butnot limited to, the methods illustrated in FIGS. 7 and 8. Anycombination of one or more computer readable non-transitory medium(s)may be utilized. The computer readable medium may be a computer readablesignal medium or a computer readable storage medium. The non-transitorycomputer storage medium stores instructions, and a processor executesthe instructions to perform the methods described herein. A computerreadable storage medium may be, for example, but not limited to, anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus, or device, or any suitable combinationof the foregoing. Any of these devices may have computer readableinstructions for carrying out the steps of the methods described abovewith reference to FIGS. 7 and 8.

The computer program instructions may be stored in a computer readablemedium that can direct a computer, other programmable data processingapparatus, or other devices to function in a particular manner, suchthat the instructions stored in the computer readable medium produce anarticle of manufacture including instructions which implement thefunction/act specified in the flowchart and/or block diagram block orblocks.

Furthermore, the computer program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other devicesto cause a series of operational steps to be performed on the computer,other programmable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

In case of implementing the systems and methods herein by softwareand/or firmware, a program constituting the software may be installedinto a computer with dedicated hardware, from a storage medium or anetwork, and the computer is capable of performing various functions ifwith various programs installed therein.

In the case where the above-described series of processing isimplemented with software, the program that constitutes the software maybe installed from a network such as the Internet or a storage mediumsuch as the removable medium. Examples of a removable medium include amagnetic disk (including a floppy disk), an optical disk (including aCompact Disk-Read Only Memory (CD-ROM) and a Digital Versatile Disk(DVD)), a magneto-optical disk (including a Mini-Disk (MD) (registeredtrademark)), and a semiconductor memory. Alternatively, the storagemedium may be the ROM, a hard disk contained in the storage section ofthe disk units, or the like, which has the program stored therein and isdistributed to the user together with the device that contains them.

As will be appreciated by one skilled in the art, aspects of the systemsand methods herein may be embodied as a system, method, or computerprogram product. Accordingly, aspects of the present disclosure may takethe form of an entirely hardware system, an entirely software system(including firmware, resident software, micro-code, etc.) or an systemcombining software and hardware aspects that may all generally bereferred to herein as a “circuit,” “module”, or “system.” Furthermore,aspects of the present disclosure may take the form of a computerprogram product embodied in one or more computer readable medium(s)having computer readable program code embodied thereon.

Any combination of one or more computer readable non-transitorymedium(s) may be utilized. The computer readable medium may be acomputer readable signal medium or a computer readable storage medium.The non-transitory computer storage medium stores instructions, and aprocessor executes the instructions to perform the methods describedherein. A computer readable storage medium may be, for example, but notlimited to, an electronic, magnetic, optical, electromagnetic, infrared,or semiconductor system, apparatus, or device, or any suitablecombination of the foregoing. More specific examples (a non-exhaustivelist) of the computer readable storage medium include the following: anelectrical connection having one or more wires, a portable computerdiskette, a hard disk, a random access memory (RAM), a Read Only Memory(ROM), an Erasable Programmable Read Only Memory (EPROM or Flashmemory), an optical fiber, a magnetic storage device, a portable compactdisc Read Only Memory (CD-ROM), an optical storage device, a“plug-and-play” memory device, like a USB flash drive, or any suitablecombination of the foregoing. In the context of this document, acomputer readable storage medium may be any tangible medium that cancontain, or store a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including, but not limited to, wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent disclosure may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java, Smalltalk, C++, or the like and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The program code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer, or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider).

The flowchart and block diagrams in the figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to varioussystems and methods herein. In this regard, each block in the flowchartor block diagrams may represent a module, segment, or portion of code,which comprises one or more executable instructions for implementing thespecified logical function(s). It should also be noted that, in somealternative implementations, the functions noted in the block mightoccur out of the order noted in the figures. For example, two blocksshown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

Many computerized devices are discussed above. Computerized devices thatinclude chip-based central processing units (CPU's), input/outputdevices (including graphic user interfaces (GUI), memories, comparators,processors, etc. are well-known and readily available devices producedby manufacturers such as Dell Computers, Round Rock Tex., USA and AppleComputer Co., Cupertino Calif., USA. Such computerized devices commonlyinclude input/output devices, power supplies, processors, electronicstorage memories, wiring, etc., the details of which are omittedherefrom to allow the reader to focus on the salient aspects of theembodiments described herein. Similarly, scanners and other similarperipheral equipment are available from Xerox Corporation, Norwalk,Conn., USA and the details of such devices are not discussed herein forpurposes of brevity and reader focus.

The terms printer or printing device as used herein encompasses anyapparatus, such as a digital copier, bookmaking machine, facsimilemachine, multi-function machine, etc., which performs a print outputtingfunction for any purpose. The details of printers, printing engines,etc., are well known by those ordinarily skilled in the art and are notdescribed in detail herein to keep this disclosure focused on thesalient features presented. The systems and methods herein can encompassdevices that print in color, monochrome, or handle color or monochromeimage data. All foregoing systems and methods are specificallyapplicable to electrostatographic and/or xerographic machines and/orprocesses.

The terminology used herein is for the purpose of describing particularsystems and methods only and is not intended to be limiting of thisdisclosure. As used herein, the singular forms “a”, “an”, and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof.

In addition, terms such as “right”, “left”, “vertical”, “horizontal”,“top”, “bottom”, “upper”, “lower”, “under”, “below”, “underlying”,“over”, “overlying”, “parallel”, “perpendicular”, etc., used herein, areunderstood to be relative locations as they are oriented and illustratedin the drawings (unless otherwise indicated). Terms such as “touching”,“on”, “in direct contact”, “abutting”, “directly adjacent to”, etc.,mean that at least one element physically contacts another element(without other elements separating the described elements). Further, theterms ‘automated’ or ‘automatically’ mean that once a process is started(by a machine or a user), one or more machines perform the processwithout further input from any user.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescriptions of the various systems and methods of the presentdisclosure have been presented for purposes of illustration, but are notintended to be exhaustive or limited to the systems and methodsdisclosed. Many modifications and variations will be apparent to thoseof ordinary skill in the art without departing from the scope and spiritof the described systems and methods. The terminology used herein waschosen to best explain the principles of the systems and methods, thepractical application or technical improvement over technologies foundin the marketplace, or to enable others of ordinary skill in the art tounderstand the systems and methods disclosed herein.

It will be appreciated that the above-disclosed and other features andfunctions, or alternatives thereof, may be desirably combined into manyother different systems or applications. Various presently unforeseen orunanticipated alternatives, modifications, variations, or improvementstherein may be subsequently made by those skilled in the art which arealso intended to be encompassed by the following claims. Unlessspecifically defined in a specific claim itself, steps or components ofthe systems and methods herein cannot be implied or imported from anyabove example as limitations to any particular order, number, position,size, shape, angle, color, or material.

1. A method, comprising: receiving a print job into a print enginecomprising a processor, said processor comprising a special purposemachine that is specialized for processing image data, said print jobcomprising an image; producing, with said processor, a threshold arrayof pixel values for each color plane of said image by applying ahalftone screen associated with said print engine, said halftone screenincluding separate halftone frequencies and different threshold valuesfor each color plane of said image, said halftone frequencies and saidthreshold values having been established during calibration of saidprint engine; generating, with said processor, a mask for each saidcolor plane of said image to be applied to said halftone screen, saidgenerating said mask comprising: grouping said pixel values for saidthreshold array into a selected number of clusters, arranging saidclusters into a cluster array using one pixel value from each cluster,and identifying pixel values to remove from said threshold array, saididentifying said pixel values comprising locating each said pixel valuein said cluster array and selecting a pixel value from each cluster tobe removed, said mask being controlled to avoid removing two consecutivepixels from said image; and applying, using said processor, said mask tosaid threshold array, creating a modified threshold array, said modifiedthreshold array corresponding to reduced toner usage for a renderedimage.
 2. The method according to claim 1, further comprising: applyingsaid modified threshold array to said image of said print job, usingsaid processor, producing a modified rendered image; and sending saidmodified rendered image to an image output device associated with saidprint engine.
 3. (canceled)
 4. The method according to claim 1, furthercomprising: scaling said generating said mask for selected levels oftoner saving.
 5. The method according to claim 1, said receiving saidprint job further comprising: receiving a PDL file; parsing said PDLfile; identifying objects from said PDL file; and identifying individualcolor planes for said objects.
 6. The method according to claim 1,further comprising: receiving, in said processor, indication of tonerlevel for a color of said color plane being below a predeterminedthreshold level; and applying, using said processor, said mask to saidthreshold array for only said color of said color plane below saidpredetermined threshold level.
 7. A method comprising: receivingdigitized pixels for an image comprising color planes of differentcolors into a print engine comprising a processor, said processorcomprising a special purpose machine that is specialized for processingimage data, said digitized pixels comprising continuous image data;applying, using said processor, a halftone screen to said digitizedpixels of said continuous image data, said halftone screen includingseparate halftone frequencies and different threshold values for eachcolor plane of said image, said halftone frequencies and said thresholdvalues having been set during calibration of said print engine, and saidhalftone frequencies being selected to reduce banding and imageartifacts in a rendered image, said applying said halftone screen tosaid digitized pixels producing a threshold array of pixel values;generating, by said processor, a mask to be applied to said halftonescreen for each of said color planes of said image, said generating saidmask comprising: grouping said pixel values for said threshold arrayinto a selected number of clusters, arranging said clusters into acluster array using one pixel value from each cluster, and identifyingpixel values to remove from said threshold array, said identifying saidpixel values comprising locating each said pixel value in said clusterarray and selecting a pixel value from each cluster to be removed, saidmask being controlled to avoid removing two consecutive pixels from saidimage; and translating, by said processor, said threshold array of pixelvalues to an image file; and applying, by said processor, said mask tosaid image file, removing selected pixels from said rendered image basedon said mask.
 8. (canceled)
 9. The method according to claim 7, saidgenerating said mask comprising: scaling said mask for selected levelsof toner saving.
 10. The method according to claim 7, furthercomprising: applying, using said processor, said threshold array to aninput image, generating said rendered image; and applying, using saidprocessor, said mask to said rendered image.
 11. The method according toclaim 7, further comprising: receiving, in said processor, indication oftoner level for a color of said color planes being below a predeterminedthreshold level; and applying, using said processor, said mask to saidthreshold array for only said color of said color planes below saidpredetermined threshold level.
 12. A multifunction device comprising: acontrol system comprising a processor, said processor comprising adigital image processor; a user interface connected to said controlsystem; and an image output device connected to said processor, saiduser interface providing user selection of a level of toner savings forsaid image output device, said processor receiving digitized pixels foran image comprising color planes of different colors, said digitizedpixels comprising continuous image data, said digital image processorapplying a halftone screen to said digitized pixels of said continuousimage data, said halftone screen including separate halftone frequenciesand different threshold values for each color plane of said image, saidhalftone frequencies and said threshold values having been set duringcalibration of a print engine associated with said image output device,and said halftone frequencies being selected to reduce banding and imageartifacts in a rendered image according to said image output device,said digital image processor producing a threshold array of pixel valuesusing said halftone screen, said processor generating a mask to beapplied to said halftone screen for each of said color planes of saidimage, said generating said mask comprising: grouping said pixel valuesfor said threshold array into a selected number of clusters, arrangingsaid clusters into a cluster array using one pixel value from eachcluster, and identifying pixel values to remove from said thresholdarray, said identifying said pixel values comprising locating each saidpixel value in said cluster array and selecting a pixel value from eachcluster to be removed, said mask being controlled to avoid removing twoconsecutive pixels from said image, said processor translating saidthreshold array of pixel values to an image file, said processorapplying said mask to said image file, removing selected pixels fromsaid rendered image, and said processor sending said image file to saidimage output device.
 13. The multifunction device according to claim 12,further comprising: said processor receiving a print job furthercomprising said processor receiving a PDL file, said processor parsingsaid PDL file, said processor identifying objects from said PDL file,and said processor identifying individual color planes for said objectssupported by said image output device.
 14. (canceled)
 15. Themultifunction device according to claim 12, further comprising:applying, using said processor, said threshold array to an input image,generating said rendered image; and applying, using said processor, saidmask to said rendered image.
 16. The multifunction device according toclaim 12, further comprising: sensors determining toner level for eachcolor of said image output device, said control system including apredetermined threshold level for each color toner; said processorreceiving indication of toner level for a color of said color planebeing below said predetermined threshold level, and said processorapplying said mask to said threshold array for only said color of saidcolor plane below said predetermined threshold level.
 17. A methodcomprising: receiving digitized pixels for an image comprising colorplanes of different colors into a print engine comprising a processor,said processor comprising a special purpose machine that is specializedfor processing image data, said digitized pixels comprising continuousimage data; applying, using said processor, a halftone screen to saiddigitized pixels of said continuous image data, said halftone screenincluding separate halftone frequencies and different threshold valuesfor each color plane of said image, said halftone frequencies and saidthreshold values having been set during calibration of said printengine; producing, by said processor, a threshold array of pixel valuesby applying said halftone screen; generating, by said processor, a maskto be applied to said halftone screen for each of said color planes ofsaid image, said generating said mask comprising: grouping said pixelvalues for said threshold array into a selected number of clusters,arranging said clusters into a cluster array using one pixel from eachcluster, and identifying pixel values to remove from said thresholdarray, said identifying said pixel values comprising locating each saidpixel value in said cluster array and selecting a pixel value from eachcluster to be removed, said mask being controlled to avoid removing twoconsecutive pixels from said image; and applying, by said processor,said mask to said threshold array, creating a modified threshold array,said modified threshold array corresponding to reduced toner usage forrendering said image. 18-19. (canceled)
 20. The method according toclaim 17, further comprising: applying, using said processor, saidthreshold array to an input image, generating a rendered image; andapplying, using said processor, said mask to said rendered image. 21.The method according to claim 20, further comprising: translating, usingsaid processor, said threshold array of pixel values to an image file,applying, using said processor, said mask to said image file, removingselected pixels from said rendered image, and sending, using saidprocessor, said image file to an image output device associated withsaid print engine.
 22. The method according to claim 17, furthercomprising: receiving, using said processor, a selected level of tonersaving; and scaling, using said processor, said generating said mask forsaid selected level of toner saving.
 23. The method according to claim17, said receiving a print job further comprising: receiving a PDL file;parsing said PDL file; identifying objects from said PDL file; andidentifying individual color planes for said objects.
 24. The methodaccording to claim 17, further comprising: receiving, in said processor,indication of toner level for a color of said color plane being below apredetermined threshold level; and applying, using said processor, saidmask to said threshold array for only said color of said color planebelow said predetermined threshold level.